1. Field of the Invention
This invention relates to a coloring agent for foodstuffs and the like and, more particularly, this invention relates to a water-soluble curcumin-gelatin complex and a method for preparing the same.
2. Description of the Prior Art
Turmeric is the dried rhizome of the plant Curcuma Longa L. It is used in foods for its coloring ability and less frequently for its flavor. Curcumin is the compound in turmeric that is primarily responsible for its coloring ability. The dried turmeric rhizomes generally contain about 5% curcumin.
Ground turmeric may be extracted with organic solvents to remove the curcumin and the fixed and volatile oils from the cellulose plant material of the rhizomes, to form oleoresins. Solvents such as isopropanol, ethanol, acetone, and ethylene dichloride and others are typically used to prepare oleoresins of turmeric, which may typically contain about 30% curcumin, 30% volatile oils, 30% fixed oils, and 10% polysaccharides. Oleoresins are used by the food industry to color pickles, baked goods, poultry products, and in seasoning mixtures for various other food products.
The fixed and volatile oil portions of the ground spice or the oleoresin are responsible for the characteristic flavor and bitterness of turmeric. This flavor and bitterness is sometimes undesirable in the finished food product. The fixed and volatile oils can be removed from oleoresins by extraction with an organic solvent which is different from that used in the preparation of the oleoresin, from rhizomes, or by physically removing curcumin crystals from the oleoresin by filtration or centrifugation. The resulting volatile oil-free product is known as "debitterized" or "defatted" turmeric.
Curcumin is substantially insoluble in water. Since most food systems contain a significant amount of water, curcumin will not color these systems without the aid of a synthetic chemical emulsifier of some type.